1. Field of the Invention
An embodiment of the present invention relates generally to a mask assembly, and more particularly, to a mask assembly used in a thin film deposition process such as an organic emission layer or a metal layer, and a manufacturing method thereof.
2. Description of the Related Art
As a flat panel display device, a liquid crystal display (LCD) device and an organic light emitting diode (OLED) display device are widely used. The flat panel display device includes a metal layer of a predetermined pattern, and in a case of the organic light emitting diode (OLED) display device, an organic emission layer of the predetermined pattern is formed for every pixel. A deposition method using a mask assembly as a method of forming the metal layer and the organic emission layer may be applied.
The mask assembly includes a mask having an opening corresponding to the pattern of the metal layer or the organic emission layer and a frame supporting the mask. In a division mask method, the mask is divided into a plurality of unit masks formed with a belt shape, and each unit mask is fixed to the frame by welding in a state that the unit mask is extended in a length direction. The division mask method allows good selection and is easy to repair.
The unit mask is applied with a tension force in one direction such that the unit mask is elongated in the length direction of the tension direction, however, a contraction is generated in a direction crossing the tension direction, that is, a width direction, and thereby the entire mask may be wrinkled. This wrinkle becomes more serious as a width of the unit mask is increased.
Also, both ends of the unit mask are fixed to a clamp to be extended, and in this case, the unit mask is formed of a thin metal plate such that the wrinkle may be generated about the ends fixed to the clamp when the unit mask is capable of enduring a pulling force by the clamp. The wrinkle that is generated at the ends of the unit mask is expanded to the center of the unit mask in which an opening is positioned thereby generating a deposition defect.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.